The following generally relates to a power tool and, more particularly, to a power tool having an output shaft for driving a working element, a fastening member for clamping the working element to one end of the output shaft, and a moving device for enabling the fastening member to move between a release position in which the fastening member may be removed from the output shaft by disengaging from the moving device and a clamping position in which the fastening member can support the end of the output shaft so as to firmly clamp the working element by locking the moving device and the cooperation of a spring member.
U.S. Pat. No. 6,569,001 discloses a power tool having a quick clamping device. The power tool is an angle grinder with a hollow spindle mounted therein. A clamping device is mounted in the hollow spindle, which can be moved between a clamping position and a release position along the axial direction of the spindle. The clamping device comprises a clamping flange with a threaded pin in the middle thereof. The clamping flange is used to mate with a counter flange on one end of the hollow spindle so as to clamp the working element therebetween. The hollow spindle is also provided with a thrust piece therein for mating with the threaded pin. In the clamping position, the threaded pin is threaded into the thrust piece and kept in the clamping position under the action of the spring force, and in the release position, the thrust piece pushes the threaded pin so as to force the clamping flange to overcome the action of the spring force and disengage from the surface of the clamped working element. In this state, when the clamping flange rotates relative to the clamped working element, there is no friction therebetween, so the threaded pin of the clamping flange can be threaded out of the thrust piece without any tools. Thereby it is convenient to replace the working element. Although this clamping device can substantially clamp the working element to the output shaft of the power tool without any tools, this clamping device is only suitable for clamping the working element which is driven to rotate. If the working element is driven by an oscillation device to oscillate back and forth about the longitudinal axis of the output shaft, it may cause a relative large mutation torque and a large impact in the two directions of the rotation. Thus it cannot make sure that the working element may be firmly clamped by a known clamping device.
The power tool in the prior art also has a defect that the working element clamped on the power tool cannot be adjusted between multiple angles. The working element is either in a clamping state for operation or in a release state for removing. When it is needed to adjust an angle of the working element, the working element must be removed and clamped again. Thus the operation is laborious and time consuming, which is not convenient.